Extended duration insect repellent composition and method of application to the skin

ABSTRACT

Disclosed is an insect repellent composition. The composition has an amount of an insect repellent active effective to repel insects when the composition is applied to the skin, and an amount of a urethane polymer sufficient to form a film on the surface of the skin. The composition also has a cosmetically-acceptable vehicle. Also disclosed is a method of repelling insects from the skin by applying the composition to the skin.

RELATED APPLICATIONS

[0001] This application claims priority from U.S. patent applicationSer. No. 09/724,160 filed on Nov. 28, 2000 and PCT Patent ApplicationSerial No. PCT/US01/44299 filed on Nov. 27, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an insect repellent composition.More particularly, the present invention relates to an insect repellentexhibiting extended duration of repellency on the skin. Further, thepresent invention relates to such a composition exhibiting water, sweat,and wear resistance. As used herein, the term “insect” is intended tomean any insect or arachnid.

[0004] 2. Description of the Prior Art

[0005] Insect repellent compositions are available commercially in avariety of product forms, such as aerosol and pump sprays, creams,lotions and gels. Depending upon the product form, the compositions maybe administered to both the skin and to clothing. The compositions maybe administered in preparation for a variety of outdoor situations, suchas picnicking, hiking, fishing, swimming and exercise.

[0006] A common problem associated with insect repellent compositions isa lack of duration of repellency. This translates into insufficientrepellency and the need to re-apply often. Insect repellent compositionsmay wash off from exposure to water, sweating and/or physical contactwith the skin.

[0007] It would be desirable to increase the duration of repellency ofinsect repellent compositions on the skin. It would further be desirableto have insect repellent compositions that resist removal by exposure towater, sweating and physical contact.

[0008] U.S. Pat. No. 4,913,897 to Chvapil et al. is directed to hydrogelcompositions that form films on the surface of the skin to protect itagainst exposure to toxic substances and infections. This patentprovides that such films may also contain an insect repellent. Theurethane polymers of the present invention are not hydrogels nor do theyform hydrogels in the present invention.

SUMMARY OF THE INVENTION

[0009] It is an object of the present invention to provide an insectrepellent composition exhibiting extended duration and enhanced degreeof repellency on the skin.

[0010] It is another object of the present invention to provide such acomposition that provides even application and is water, sweat, and wearresistant.

[0011] It is a further object of the present invention to provide such acomposition that is aesthetically acceptable.

[0012] These and other objects of the present invention are achieved byan insect repellent composition having an amount of an insect repellentactive sufficient to repel insects when the composition is applied tothe skin. The composition also has an amount of urethane polymersufficient to form a thin, substantially continuous film on the skin.The composition also has a cosmetically acceptable vehicle.

[0013] Further according to the present invention, there is provided amethod of repelling insects from the skin. The composition describedabove is applied to the skin. A thin urethane film, that is differentfrom a hydrogel film, remains on the skin to enhance the function andeffectiveness of the insect repellent. This urethane film issubstantially uniform and provides superior coverage over the peaks andvalleys of the skin surface, allowing for reduction of unprotected skinareas.

DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a bar graph illustrating the duration of insectrepellency with varying levels of urethane polymers.

[0015]FIG. 2 is a view of a photograph of showing the topography of anartificial skin substrate without the application of the presentinvention.

[0016]FIG. 3 is a view of a photograph showing the topography of a skinsubstrate with and without the application of an acrylic polymer not ofthe present invention.

[0017]FIG. 4 is a view of a photograph showing the appearance of a skinsubstrate with and without the application of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention surprisingly found that an insect repellentcomposition can be produced that exhibits extended duration ofrepellency on the skin, and also enhanced insect repellency. Inaddition, the composition has superior spread characteristics on theskin. The composition may also exhibit water, sweat and wear resistance.

[0019] The composition can be formulated to be substantially transparentor otherwise aesthetically acceptable to impart a pleasant feel orsensation to the skin.

[0020] When applied to the skin, the present composition leaves auniform film on the surface of the skin. The composition, which exhibitssuperior spread characteristics, provides more uniform and consistentcoverage on the skin. The film has been found to maintain the durationof the insect repellent active(s) for a longer period of time than itwould otherwise remain without the urethane polymer. The film alsoaffords sustained release of the active. Additionally, enhancedresistance to water, sweat, and wear may be observed. In view of theforegoing advantages, the film has an enhanced degree of insectrepellency for a given amount of insect repellent active employed. Thus,the amount of insect repellent active applied to the skin can beminimized.

[0021] The film-forming component of the present composition is aurethane polymer resin. Urethane polymers are formed by reactions ofdiisocyanate and glycol monomers. Preferred urethane polymer resins foruse in the present invention are of the following formula:

[0022] wherein R and R′ are, independently, any linear or branchedalkyl, alkylene, aliphatic or aromatic group having from 1 to about 30carbon atoms, preferably about 6 to about 24 carbon atoms, and n is aninteger from 2 to about 1000. When R′ is cyclic, it preferably contains6 or more carbon atoms. Urethane polymer resins useful in the presentinvention can be either hydrophobic or hydrophilic.

[0023] The most preferred urethane polymer resins are those referred toin the art as Polyurethane-1, Polyurethane-2, Polyurethane-4,Polyurethane-5 or mixtures thereof. These urethane polymer resins aredescribed in the International Cosmetic Ingredient Dictionary andHandbook, 8^(th) edition, Printed Edition Pages 1152-1153, which isincorporated herein by reference.

[0024] The urethane polymer is present in an amount about 0.1 wt. % toabout 20 wt. % based on the total weight of the composition. The amountof the urethane polymer is preferably about 0.5 wt. % to about 10 wt. %,and, most preferably, about 1 wt. % to about 5 wt. %, based on the totalweight of the composition.

[0025] The insect repellent or insect repellent active employed in thepresent composition may be any known in the art. Such actives that canbe used in the present invention include, but are not limited to, N,Ndiethyl-m-toluamide (DEET), ethyl butylacetylaminopropionate (IR3535 byMerck Co.), hydroxy-ethyl isobutyl piperidine carboxylate(1-piperidinecarboxylic acid) (Bayer KBR 3023), oil of citronella, soybean oil, lemon grass oil, geranium/geraniol oil, p-menthane-3,8-diol,or mixtures thereof. Other actives that can be used in the presentinvention are disclosed in U.S. Pat. Nos. 5,130,136 and 5,698,209, whichare incorporated herein by reference.

[0026] The amount of insect repellent active is about 0.1 wt. % to about70 wt. % based on the total weight of the composition. The amount ofinsect repellent active is preferably about 0.1 wt. % to about 25 wt. %,and, most preferably, about 5 wt. % to about 25 wt. %, based on thetotal weight of the composition.

[0027] The present composition may take any form known in the art. Suchforms include, but are not limited to, a cream, lotion, gel, solution,ointment, towelette, mousse, stick, or pump spray or aerosol. If anaerosol spray, the composition may contain propellents, such ashydrocarbons, hydrofluorocarbons, chlorofluorocarbons and ethers. Thecomposition may be aqueous or anhydrous. The composition may further bein an emulsion form.

[0028] The present composition preferably has a vehicle. Such vehiclesmay be any known in the art including, for example, water; vegetableoils; esters such as octyl palmitate, isopropyl myristate and isopropylpalmitate; ethers such as dicapryl ether and dimethyl isosorbide;alcohols such as ethanol and isopropanol; fatty alcohols such as cetylalcohol, stearyl alcohol and behenyl alcohol; isoparaffins such asisooctane, isododecane and isohexadecane; silicone oils such ascyclomethicone, dimethicone, dimethicone cross-polymers, polysiloxanesand their derivatives, preferably organomodified derivatives;hydrocarbon oils such as mineral oil, petrolatum, isoeicosane andpolyisobutene; polyols such as propylene glycol, glycerin, butyleneglycol, pentylene glycol and hexylene glycol; waxes such as beeswax andbotanical waxes; and mixtures of the foregoing.

[0029] The vehicle is about 0.1 wt. % to about 99.8 wt. % of the totalweight of the composition. Preferably, the vehicle is about 10 wt. % toabout 93 wt. % of the total weight of the composition.

[0030] Optionally, the present composition may further include asunscreen. The sunscreen may be any sunscreen know in the art. Suchsunscreens include, but are not limited to, oxybenzone, sulisobenzone,dioxybenzone, menthyl antranilate, para aminobenzoic acid, deamethoxycinnamate, octyl methoxycinnamate, octocrylene, drometrizoletrisiloxane, octyl salicylate, homomenthyl salicylate, octyl dimethylPABA, TEA salicylate, titanium dioxide, zinc oxide, butylmethoxydibenzoylmethane, methyl benzilidene camphor, octyl triazone,terephthalydiene dicamphor sulfonic acid, ethyl PABA, hydroxymethylphenyl benzotriazole, methylenebis-benzotriazoyltetramethylbutylphenol (MBBT), bis-ethylhexyl oxyphenolmethoxyphenol triazine (BEMT), and mixtures thereof. Other sunscreensinclude those disclosed in U.S. Pat. No. 5,000,937, which isincorporated herein.

[0031] The sunscreen is preferably about 1 wt. % to about 45 wt. % ofthe total weight of the composition. Preferably, the sunscreen is about2 wt. % to about 35 wt. % of the total weight of the composition. Mostpreferably, the sunscreen protects against both UVA and UVB radiation,and provides a SPF factor of at least about 2 and more preferably atleast about 4. The preferred range of SPF protection is about 10 toabout 50 and most preferably about 15 to about 30.

[0032] Further optionally, the present composition may have one or moreof the following additional ingredients: anesthetics, anti-allergenics,antifungals, anti-inflammatories, antiseptics, chelating agents,colorants, depigmenting agents, emollients, emulsifiers, exfollients,fragrances, humectants, lubricants, moisturizers, pharmaceutical agents,preservatives, skin penetration enhancers, stabilizers, surfactants,thickeners, viscosity modifiers, vitamins or any combinations of theseingredients.

EXAMPLES 1 AND 2 AND CONTROL

[0033] Two compositions of the present invention were tested forduration of insect repellency. A control composition (“the Control”) waslikewise tested.

[0034] The compositions of Examples 1 and 2 had polyurethaneconcentrations of 1.0 wt. % and 2.0 wt. %, respectively, based upon thetotal weight of the compositions. The Control did not have anypolyurethane (zero wt. %). The polyurethane resin employed wasPolyurethane-1. All the compositions had 20 wt. % of IR3535 (Merck) asan insect repellent active, and q.s. with a mixture of alcohol andwater.

[0035] The duration of insect repellency was tested on five subjects ina cage test utilizing a 1 cubic meter cage containing 200 mosquitoes.

[0036] The results are set forth in FIG. 1. The inclusion ofpolyurethane significantly increased the duration of repellency at boththe 1.0 wt. % and 2.0 wt. % levels.

Optical Profilometry of Polymer Films

[0037] To determine the attributes of the present invention, an opticalprofilometry study of the present invention was performed on samples ofan artificial skin substrate. FIG. 2 shows a 3-dimensional interactivedisplay of the bare substrate as viewed under an optical profilermicroscope. The peaks and valleys of the skin surface are clearlypronounced. As a comparison, tape was placed over the left side of asubstrate sample. An insect repellent composition containing aconventional acrylic film forming polymer was applied to the right sideof the substrate, allowed to dry and the tape was removed. A digitalimage was taken of this substrate surface using a Wyko NT1000 OpticalProfiler made by Vecco. As is evident in FIG. 3, there was bleeding ofthe insect repellent composition under the tape, as well as non-uniformcoverage of the peaks and valleys over which it was applied. As afurther comparison, similar insect repellent composition having theurethane polymer film former of the present invention was prepared. Tapewas placed over the left side of a substrate sample, and the inventivecomposition was applied to the right side and allowed to dry. The tapewas removed and a digital image was taken of the substrate surface. Asis evident from FIG. 4, this composition stayed where applied and didnot run under the tape. Moreover, there was maximum, substantiallyuniform coverage of the peaks and valleys over which it was applied.

[0038] It should be understood that the foregoing description is onlyillustrative of the present invention. Various alternatives andmodifications can be devised by those skilled in the art withoutdeparting from the invention. Accordingly, the present invention isintended to embrace all such alternatives, modifications and variancesthat fall within the scope of the appended claims.

What is claimed is:
 1. An insect repellent composition, comprising: anamount of an insect repellent active effective to repel insects when thecomposition is applied to skin; and an amount of a urethane polymersufficient to form a film on the surface of the skin.
 2. The compositionof claim 1, further comprising a cosmetically-acceptable vehicle.
 3. Thecomposition of claim 1, wherein the urethane polymer has the followingformula:

wherein R and R′ are, independently, any linear or branched alkyl,alkylene, aliphatic or aromatic group having from 1 to about 30 carbonatoms, and n is an integer from 2 to about
 1000. 4. The composition ofclaim 3, wherein R′ is cyclic and has 6 or more carbon atoms.
 5. Thecomposition of claim 1, wherein the urethane polymer is about 0.1 wt. %to about 20 wt. % based on the total weight of the composition.
 6. Thecomposition of claim 1, wherein the urethane polymer is about 0.5 wt. %to about 10 wt. % based on the total weight of the composition.
 7. Thecomposition of claim 1, wherein the amount of insect repellent active isabout 0.1 wt. % to about 70 wt. % based on the total weight of thecomposition.
 8. The composition of claim 1, wherein the urethane polymeris selected from the group consisting of Polyurethane-1, Polyurethane-2,Polyurethane-4, Polyurethane-5, and mixtures thereof.
 9. The compositionof claim 1, wherein the insect repellent active is selected from thegroup consisting of N,N diethyl-m-toluamide, ethylbutylacetylaminopropionate, hydroxy-ethyl isobutyl piperidinecarboxylate, oil of citronella, soy bean oil, lemon grass oil,geranium/geraniol oil, p-menthane-3,8-diol, and mixtures thereof. 10.The composition of claim 1, wherein the composition is in the formselected from the group consisting of a cream, lotion, gel, solution,towelette, mousse, stick, ointment, spray, and aerosol.
 11. Thecomposition of claim 1, further comprising a sunscreen.
 12. Thecomposition of claim 1, wherein the sunscreen is selected from a groupconsisting of oxybenzone, sulisobenzone, dioxybenzone, menthylanthranilate, para aminobenzoic acid, octyl methoxycinnamate,octocrylene, drometrizole trisiloxane, octyl salicylate, homomenthylsalicylate, octyl dimethyl PABA, TEA salicylate, titanium dioxide, zincoxide, butylmethoxy dibenzoylmethane, methyl benzilidene camphor, octyltriazone, terephthalydiene dicamphor, sulfonic acid, ethyl PABA, hydroxymethylphenyl benzotriazole, methylenebis-benzotriazoyltetramethylbutylphenol, bis-octyloxyphenolmethoxyphenol triazine, and mixtures thereof.
 13. The composition ofclaim 12, wherein the sunscreen is selected from a group consisting ofoxybenzone, octyl methoxycinnamate, octocrylene, octyl salicylate,titanium dioxide, zinc oxide, butylmethoxy dibenzoylmethane, methylenebis-benzotriazoyltetramethylbutylphenol, bis-octyloxyphenolmethoxyphenol triazine, and mixtures thereof.
 14. The composition ofclaim 1, wherein the urethane polymer does not form a hydrogel or ahydrogel film.
 15. An insect repellent composition, comprising: anamount of an insect repellent active effective to repel insects when thecomposition is applied to skin; about 0.1 wt. % to about 20 wt. % basedon the total weight of the composition of a urethane polymer, whereinthe urethane polymer forms a film on the surface of the skin; and acosmetically-acceptable vehicle.
 16. The composition of claim 15,wherein the urethane polymer has the following formula:

wherein R and R′ are, independently, any linear or branched alkyl,alkylene, aliphatic or aromatic group having from 1 to about 30 carbonatoms, and n is an integer from 2 to about
 1000. 17. The composition ofclaim 16, wherein R′ is cyclic and has 6 or more carbon atoms.
 18. Thecomposition of claim 15, wherein the urethane polymer is selected fromthe group consisting of Polyurethane-1, Polyurethane-2, Polyurethane-4,Polyurethane-5, and mixtures thereof.
 19. A method of repelling insectsfrom the skin, comprising applying to the skin the composition ofclaim
 1. 20. The method of claim 19, wherein the urethane polymer isabout 0.1 wt. % to about 20 wt. % based on the total weight of thecomposition.
 21. The method of claim 19, wherein the urethane polymerhas the following formula:

wherein R and R′ are, independently, any linear or branched alkyl,alkylene, aliphatic or aromatic group having from 1 to about 30 carbonatoms, and n is an integer from 2 to about
 1000. 22. The composition ofclaim 21, wherein R′ is cyclic and has 6 or more carbon atoms.
 23. Themethod of claim 19, wherein the polyurethane is selected from the groupconsisting of Polyurethane-1, Polyurethane-2, Polyurethane-4,Polyurethane-5, and mixtures thereof.
 24. The method of claim 19,wherein the insect repellent active is about 0.1 wt. % to about 70 wt. %based on the total weight of the composition.
 25. An insect repellentcomposition comprising: an effective amount of an insect repellent; afilm-forming urethane polymer; and a volatile component, wherein thecomposition is dispensed from a spray container.
 26. The composition ofclaim 25, wherein the composition is substantially anhydrous.
 27. Thecomposition of claim 25, wherein the spray container is selected fromthe group consisting of a pump spray container and an aerosol spraycontainer.
 28. The composition of claim 25, wherein the volatilecomponent is selected from the group consisting of one or more alcohols,hydrocarbons, ethers, silicones, water, and mixtures thereof.